[Lactate Dehydrogenase - Old Tumour Marker in the Light of Current Knowledge and Preanalytic Conditions]. / Laktátdehydrogenáza - starý nádorový marker ve svetle soucasných poznatku a v preanalytických souvislostech.

With the development and subsequent clinical applications of anticancer immuno-and angiomodulatory therapies and expanded knowledge on significance of tumor microenvironment for disease prognosis and treatment outcome, a classical blood analyte, lactate dehydrogenase (LDH), gains in importance as a tumor marker reflecting to some extent immunosupressive and angiogenic tumour milieu. Physical extravascular hemolysis due to complicated or inaccurate blood sampling interferes strongly with quantification of LDH in serum/plasma samples. Upon correlating circulating hemoglobin level with LDH catalytic activities in 99,937 plasma samples we quantified hemolysis interference with LDH plasma levels. An increment of LDH (µkat/l) caused by hemolysis is equal to 0.002 times circulating hemoglobin level (mg/l). Thus, hemolysis interference can be mathematically subtracted from measured LDH using a formula: [LDH (measured) (µkat/l) - 0.002 × circulating hemoglobin (mg/l) ]. In other words, each increment of hemolysis equal to 100mg/l of circulating hemoglobin will result to LDH increase equal to 0.2 µkat/l. As one of the emerging predictors of treatment outcome, a cancer prognostic biomarker and dynamic tumor marker, serum/plasma LDH concentration needs to be interpreted with respect to reported hemolysis level. Also, for these purposes, quantitative determination of serum/plasma levels of free circulating hemoglobin has to be routinely performed.Key words: lactate dehydrogenase - hemolysis - preanalytical error This work was supported by MEYS via NPS I for RECAMO2020 (LO1413). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 13. 3. 2017Accepted: 26. 3. 2017.

[Circulating Myeloid Suppressor Cells and Their Role in Tumour Immunology]. / Cirkulující myeloidní supresorové bunky a jejich úloha v nádorové imunologii.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) are heterogenic population of multipotent progenitors of myeloid lineage. For their immunosuppressive effect, MDSC are responsible for tumour escape from the host immune surveillance. Furthermore, MDSCs support tumour by promotion of angiogenesis and metastasis. Membrane markers of human MDSCs are myeloid markers CD11b and CD13, these cells are HLA-Drlow/- and expression of CD15 or CD14 differentiate them into granulocytic (Gr-MDSCs) and monocytic (Mo-MDSCs), resp. PATIENTS AND METHODS: Using flow cytometry, we investigated Mo-MDSC counts in peripheral blood of non-cancer individuals - control group (n = 61), breast (n = 39) and colorectal (n = 52) cancer patients. These cells were detected as CD45+CD11b+CD33+CD14+HLA-Drlow/- and quantified as percentage of total white blood cells and as absolute count. RESULTS: In control group, circulating Mo-MDSCs was gender-and age-independent and the average value was 1.09% and 0.073 × 109/l. Breast cancer patients had higher circulating Mo-MDSCs compared to control group with average values: 3.57% and 0.229 × 109/l (p < 0.001) and we also observed increase in Mo-MDSC number after granulopoietic growth factors administration (p = 0.043). Colorectal cancer patients had higher average number of circulating Mo-MDSCs compared to control group: 1.71% a 0.125 × 109/l (p = 0.003) and its number did not correlate with tumour clinicopathological stage, localization of primary tumour (colon vs. rectum), site (left vs. right) and microsatellite instability. CONCLUSION: Increased number of MDSCs in circulation and within tumour microenvironment has been associated with immune suppression and tumour progression. Colorectal cancer patients at diagnosis showed higher circulating Mo-MDSCs possibly reflecting immunosuppressive effect of tumour microenvironment. Change of Mo-MDSC number from baseline level need to be evaluated in the context of CRC patients outcome. Recombinant granulopoietic growth factors increase number of circulating Mo-MDSCs and the effect of this phenomenon on cancer prognosis remains to be elucidated.Key words: myeloid-derived suppressor cells - colorectal cancer - breast cancer - immunology - immunosuppression - G-CSF This work was supported by MEYS by NPU I (LO1413), grant AZV 16-31966A and MH DRO 00209805. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 11. 3. 2017Accepted: 26. 3. 2017.

[New Indings in Methotrexate Pharmacology -  Diagnostic Possibilities and Impact on Clinical Care]. / Nové poznatky ve farmakologii methotrexátu -  diagnostické moznosti a klinický význam.

Methotrexate is an anti-cancer drug used to treat several malignancies including pediatric acute lymphoblastic leukemia and choriocarcinoma. Despite recent advances in cancer chemotherapy, it remains a mainstay of therapy since its discovery in the early second half of the previous century. Moreover, low-dose methotrexate is a gold standard antirheumatic drug in the treatment of rheumatoid arthritis, psoriasis, systemic scleroderma and other autoimmune disorders. Side effects of methotrexate treatment are well known and described; however, their occurrence may often be unpredictable due to lack of specific biomarkers of toxicity. Methotrexate plasma levels are routinely monitored by therapeutic drug monitoring, nevertheless, occurrence and concentrations of its metabolites are not measured. During methotrexate treatment 7- hydroxymethotrexate and 2,4- diamino- N10- mehylpteroic acid appear in plasma. The latter can further be hydroxylated and glucuronidated resulting in five possible extracellular methotrexate metabolites. In addition, methotrexate is intracellularly converted to its active polyglutamylated forms. Therapeutic efficacy is dependent on formation of methotrexate polyglutamates as it keeps intracellular pool of the drug and enhances its affinity towards various target enzymes. In this study, we describe pharmacokinetic and pharmacodynamic characteristics of methotrexate metabolites. We also review methotrexate blood brain barrier transport to cerebrospinal fluid regarding its use in the prevention of leukemic central nervous system involvement and management of methotrexate toxicity with the use of carboxypeptidase- G2. Finally, we discuss laboratory methods for monitoring methotrexate metabolites and benefits of simultaneous determination of methotrexate and metabolites as possible biomarkers of therapeutic efficacy and clinical toxicity.

The role of platelets in tumour growth.

Platelets, as initial responders to vascular injury, play a very important role in the initial stages of the haemostatic process. While the role of platelets in coagulation has been well studied and documented, their role in other physiological and pathological processes is just emerging. Platelets contain many biologically active molecules and, as they adhere to sites of tumour activated or injured endothelium, many of these molecules are released into the local microenvironment leading to platelet-mediated effects on vascular tone, repair and neo-angiogenesis. Platelets are likely play important roles in the tumour microenvironment that may be thought of as "a wound that never heals".